Search

Efforts to manage living marine resources (LMRs) under climate change need projections of future ocean conditions, yet most global climate models (GCMs) poorly represent critical coastal habitats. GCM utility for LMR applications will increase with higher spatial resolution but obstacles including computational and data storage costs, obstinate regional biases, and formulations prioritizing global robustness over regional skill will persist. Downscaling can help address GCM limitations, but significant improvements are needed to robustly support LMR science and management. We synthesize past ocean downscaling efforts to suggest a protocol to achieve this goal. The protocol emphasizes LMR-driven design to ensure delivery of decision-relevant information. It prioritizes ensembles of downscaled projections spanning the range of ocean futures with durations long enough to capture climate change signals. This demands judicious resolution refinement, with pragmatic consideration for LMR-essential ocean features superseding theoretical investigation. Statistical downscaling can complement dynamical approaches in building these ensembles. Inconsistent use of bias correction indicates a need for objective best practices. Application of the suggested protocol should yield regional ocean projections that, with effective dissemination and translation to decision-relevant analytics, can robustly support LMR science and management under climate change.

Stepwise methodology for determining climate-informed multispecies biological references points for sustainable fishery harvest. This approach follows the status quo North Pacific Marine Fishery Council reviewed multispecies assessment methodology and represents a precautionary approach that minimizes inflation of Acceptable Biological Catch (ABC) due to predator release and also minimizes potential non-intuitive compound effects of climate change and fishing under declining conditions (i.e., whereby a climate informed B0 declines with climate-change and produces a lower target biomass such as B40%).

Climate change is impacting fisheries worldwide with uncertain outcomes for food and nutritional security. Using management strategy evaluations for key US fisheries in the eastern Bering Sea we find that Ecosystem Based Fisheries Management (EBFM) measures forestall future declines under climate change over non-EBFM approaches. Yet, benefits are species-specific and decrease markedly after 2050. Under high-baseline carbon emission scenarios (RCP 8.5), end-of-century (2075–2100) pollock and Pacific cod fisheries collapse in >70% and >35% of all simulations, respectively. Our analysis suggests that 2.1–2.3 °C (modeled summer bottom temperature) is a tipping point of rapid decline in gadid biomass and catch. Multiyear stanzas above 2.1 °C become commonplace in projections from ~2030 onward, with higher agreement under RCP 8.5 than simulations with moderate carbon mitigation (i.e., RCP 4.5). We find that EBFM ameliorates climate change impacts on fisheries in the near-term, but long-term EBFM benefits are limited by the magnitude of anticipated change., Ecosystem Based Management measures developed to prevent overfishing could be particularly important under climate change. Here the authors combine climate and fish stock modelling to show that EBM cap implementation reduces climate-driven fishery declines under RCP 4.5 and 8.5 before midcentury. However, there are thermal tipping points beyond which potential collapses are predicted.

A multispecies fishery management strategy evaluation (MSE) framework based on the example of the groundfish fishery in the Bering Sea and Aleutian Islands region of Alaska was used to examine the interplay between a bycatch species and three groundfish species. The study introduces a framework for a realistic multispecies fishery MSE by accounting for fleet dynamics, multispecies fishery quota allocation, and the temporal dynamics of technical interactions. The quota allocation and the fleet dynamics models were implemented using linear programming, and regression approaches were used to make a realistic projection of future users’ behavioral response to changes in the fishery. The models were calibrated and then validated using historical and out-of-sample data, respectively. The results highlight the importance of accounting for technical interactions and their interannual dynamics for both quota allocation and fleet dynamics to design a realistic multispecies fishery MSE (without them, the amount of lost yield increased). Therefore, particular attention should be paid to understanding human behavior as well as its uncertainty and to refining approaches to incorporate this information into a multispecies fishery management strategy analysis.

Three different global earth system models from the Coupled Model Intercomparison Project Phase 6 (CMIP6) were used to explore anticipated changes in the Bering Sea under high (SSP126) and low (SSP585) carbon mitigation scenarios (i.e. low and high emission scenarios), via dynamical downscaling. A multivariate pattern analysis, based on Empirical Orthogonal Functions applied to monthly time series, reveals strong coupling of changes across several biophysical variables and the global forcing itself, on both yearly and multidecadal time scales. Rising air and ocean temperatures from the global models are strongly coupled with rising regional temperatures and reduced ice cover/thickness, as well as strong changes to the phenology of the plankton food chain, including reduced biomass of large zooplankton in the fall. This method ultimately provides a compact way to estimate the changes to many regional attributes under a variety of global change scenarios. Application of this method to a broad ensemble of the CMIP6 global model air temperatures suggests that compared to present conditions, the Bering Sea shelf bottom temperatures in July will warm by an average of ∼4 degrees C by the end of the 21st century under SSP585, as compared with ∼1 degrees C under SSP126, with greatest warming focused on the outer northern shelf.

In this study we present projected changes in the Eastern Bering Sea shelf (EBS) biophysical processes in response to climate forcing scenarios from the Coupled Model Intercomparison Phase 6 (CMIP6). These changes are obtained by dynamical downscaling using a Bering Sea regional model. Surface atmospheric and ocean boundary forcing from three Earth System Models (ESMs) in CMIP6, and a low and a high emission scenario of Shared Socioeconomic Pathway (SSP126 and SSP585) of each of the ESMs are considered. Ensemble mean results suggest that, contrary to an anticipated increase in ocean stratification under warming, diminishing ice cover in response to climate forcing and resultant reduced surface freshening weakens EBS stratification in the melt season. Modeled ensemble mean phytoplankton and zooplankton biomass on the EBS exhibits subsurface maxima during the growing season; the amplitude of these maxima decreases with warming, along with a reduction in primary productivity and oxygen concentration over much of the EBS water column. Phenology of both phytoplankton and zooplankton biomass on the EBS shifts earlier, leading to an increase (decrease) in biomass averaged between April–July (August–November), while annually averaged biomass decreases under warming. Projected changes of primary and secondary plankton biomass at the end of the 21st century are not well separated between the SSP126 and SSP585 scenario in light of the large across model spread under each scenario. The projected ensemble mean warming amplitude of the EBS summer bottom temperature is largely unchanged between results forced by the Coupled Model Intercomparison Phase 5 Representative Concentration Pathway 8.5 (CMIP5 RCP8.5) and CMIP6 SSP585 scenarios. Likewise, the reduction rate of annual mean phytoplankton and large zooplankton biomass are comparable between RCP8.5 and SSP585 projections, even though the absolute amplitudes of biomass are sensitive to modeling parameters such as the solar irradiance attenuation curve. Hence, within the Bering Sea dynamical downscaling framework, projected long-term warming trends in EBS bottom temperature and plankton biomass reduction rates are robust responses to climate forcing.

Toxic pollutants such as crude oil have direct negative effects for a wide array of marine life. While mortality from acute exposure to oil is obvious, sub-lethal consequences of exposure to petroleum derivatives for growth and reproduction are less evident and sub-lethal effects in fish populations are obscured by natural environmental variation, fishing, and measurement error. We use fisheries independent surveys in the Gulf of Alaska to examine the consequences of the 1989 Exxon Valdez oil spill (EVOS) for demersal fish. We delineate areas across a range of exposure to EVOS and use spatio-temporal models to quantify the abundance of 53 species-groups over 31 years. We compare multiple community metrics for demersal fish in EVOS and Control areas. We find that areas more exposed to EVOS have more negative trends in total groundfish biomass than non-EVOS areas, and that this change is driven primarily by reductions in the abundance of the apex predator guild. We show no signature of increased variability or increased levels of synchrony within EVOS areas. Our analysis supports mild consequences of EVOS for groundfish communities, but suggests that long time-series and assessments of changes at the community level may reveal sub-lethal effects in marine communities.

Climate change in the polar regions exerts a profound influence both locally and over all of our planet. Physical and ecosystem changes influence societies and economies, via factors that include food provision, transport and access to non-renewable resources. Sea level, global climate and potentially mid-latitude weather are influenced by the changing polar regions, through coupled feedback processes, sea ice changes and the melting of snow and land-based ice sheets and glaciers.Reflecting this importance, the IPCC Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC) features a chapter highlighting past, ongoing and future change in the polar regions, the impacts of these changes, and the possible options for response. The role of the polar oceans, both in determining the changes and impacts in the polar regions and in structuring the global influence, is an important component of this chapter.With emphasis on the Southern Ocean and through comparison with the Arctic, this talk will outline key findings from the polar regions chapter of SROCC. It will synthesise the latest information on the rates, patterns and causes of changes in sea ice, ocean circulation and properties. It will assess cryospheric driving of ocean change from ice sheets, ice shelves and glaciers, and the role of the oceans in determining the past and future evolutions of polar land-based ice. The implications of these changes for climate, ecosystems, sea level and the global system will be outlined.

The Alaska Climate Integrated Modeling (ACLIM) project represents a comprehensive, multi-year, interdisciplinary effort to characterize and project climate-driven changes to the eastern Bering Sea (EBS) ecosystem, from physics to fishing communities. Results from the ACLIM project are being used to understand how different regional fisheries management approaches can help promote adaptation to climate-driven changes to sustain fish and shellfish populations and to inform managers and fishery dependent communities of the risks associated with different future climate scenarios. The project relies on iterative communications and outreaches with managers and fishery-dependent communities that have informed the selection of fishing scenarios. This iterative approach ensures that the research team focuses on policy relevant scenarios that explore realistic adaptation options for managers and communities. Within each iterative cycle, the interdisciplinary research team continues to improve: methods for downscaling climate models, climate-enhanced biological models, socio-economic modeling, and management strategy evaluation (MSE) within a common analytical framework. The evolving nature of the ACLIM framework ensures improved understanding of system responses and feedbacks are considered within the projections and that the fishing scenarios continue to reflect the management objectives of the regional fisheries management bodies. The multi-model approach used for projection of biological responses, facilitates the quantification of the relative contributions of climate forcing scenario, fishing scenario, parameter, and structural uncertainty with and between models. Ensemble means and variance within and between models inform risk assessments under different future scenarios. The first phase of projections of climate conditions to the end of the 21st century is complete, including projections of catch for core species under baseline (status quo) fishing conditions and two alternative fishing scenarios are discussed. The ACLIM modeling framework serves as a guide for multidisciplinary integrated climate impact and adaptation decision making in other large marine ecosystems.

Trait-based climate vulnerability assessments based on expert evaluation have emerged as a rapid tool to assess biological vulnerability when detailed correlative or mechanistic studies are not feasible. Trait-based assessments typically view vulnerability as a combination of sensitivity and exposure to climate change. However, in some locations, a substantial amount of information may exist on system productivity and environmental conditions (both current and projected), with potential disparities in the information available for data-rich and data-poor stocks. Incorporating this level of detailed information poses challenges when conducting, and communicating uncertainty from, rapid vulnerability assessments. We applied a trait-based vulnerability assessment to 36 fish and invertebrate stocks in the eastern Bering Sea (EBS), a data-rich ecosystem. In recent years, the living marine resources of the EBS and Aleutian Islands have supported fisheries worth more than US $1 billion of annual ex-vessel value. Our vulnerability assessment uses projections (to 2039) from three downscaled climate models, and graphically characterizes the variation in climate projections between climate models and between seasons. Bootstrapping was used to characterize uncertainty in specific biological traits and environmental variables, and in the scores for sensitivity, exposure, and vulnerability. The sensitivity of EBS stocks to climate change ranged from "low" to "high," but vulnerability ranged between "low" and "moderate" due to limited exposure to climate change. Comparison with more detailed studies reveals that water temperature is an important variable for projecting climate impacts on stocks such as walleye pollock (Gadus chalcogrammus), and sensitivity analyses revealed that modifying the rule for determining vulnerability increased the vulnerability scores. This study demonstrates the importance of considering several uncertainties (e.g., climate projections, biological, and model structure) when conducting climate vulnerability assessments, and can be extended in future research to consider the vulnerability of user groups dependent on these stocks.

International audience; Changes to our climate and oceans are already affecting living marine resources (LMRs) and the people, businesses, and economies that depend on them. As a result, the U.S. National Marine Fisheries Service (NMFS) has developed a Climate Science Strategy (CSS) to increase the production and use of the climate-related information necessary to fulfill its LMR stewardship mission for fisheries management and protected species conservation. The CSS establishes seven objectives: (1) determine appropriate, climate-informed reference points; (2) identify robust strategies for managing LMRs under changing climate conditions; (3) design decision processes that are robust to climate-change scenarios; (4) predict future states of ecosystems, LMRs, and LMR-dependent human communities; (5) determine the mechanisms of climate-change related effects on ecosystems, LMRs, and LMR-dependent human communities; (6) track trends in ecosystems, LMRs, and LMR-dependent human communities and provide early warning of change; and (7) build and maintain the science infrastructure required to fulfill NMFS mandates under changing climate conditions. These objectives provide a nationally consistent approach to addressing climate-LMR science needs that supports informed decision-making and effective implementation of the NMFS legislative mandates in each region. Near term actions that will address all objectives include: (1) conducting climate vulnerability analyses in each region for all LMRs; (2) establishing and strengthening ecosystem indicators and status reports in all regions; and (3) developing a capacity to conduct management strategy evaluations of climate-related impacts on management targets, priorities, and goals. Implementation of the Strategy over the next few years and beyond is critical for effective fulfillment of the NMFS mission and mandates in a changing climate.

Arrowtooth flounder (Atheresthes stomias) are an important predator of juvenile walleye pollock (Gadus chalcogramus) in the eastern Bering Sea (EBS) shelf and have increased 3-fold in biomass from 1977 to 2014. Arrowtooth flounder avoid the summer “cold pool” (bottom water ≤2°C) and variability in cold pool size and location has affected their spatial overlap with juvenile walleye pollock. Developing a method to account for the relationship between climate change and pollock mortality can highlight ecosystem dynamics and contribute to better assessments for fisheries management. Consequently, spatially resolved predation mortality rates were estimated within an age-structured walleye pollock stock assessment population model (based on spatial information on diet and abundance from trawl surveys), along with the effect of sea surface temperature (SST) on pollock recruitment. Projections of SST and cold pool area to 2050 were obtained (or statistically downscaled) from nine global climate models and used within an age-structure population model to project pollock abundance given estimated relationships between environmental variables and predator and prey spatial distributions, pollock recruitment, and maximum rate of arrowtooth flounder consumption. The climate projections show a wide range of variability but an overall trend of increasing SST and decreasing cold pool area. Projected pollock biomass decreased largely due to the negative effect of increased SST on pollock recruitment. A sensitivity analysis indicated that the decline in projected pollock biomass would be exacerbated if arrowtooth flounder increased their relative distribution in the EBS northwest middle shelf (an area of relatively high density of juvenile pollock) in warm years.

International audience; It is increasingly evident that climate change is having significant impacts on marine ecosystems and dependent fisheries. Yet, translating climate science into management actions and policies is an ongoing challenge. In particular, four aspects have confounded implementation of climate-resilient management: (i) regional management tools may not be well-suited for managing the same systems under climate change, (ii) individual management policies and climate research studies are often implicitly focussed on spatio-temporal scales that are rarely aligned, (iii) management approaches seldom integrate across spatio-temporal scales and are, therefore, maladapted to unidirectional change and extreme events, and (iv) challenges to modelling socio-economic implications of climate change impede projections of cumulative costs to society, disguise adaptive limits, and ultimately impact climate risk and management trade-off assessments. We suggest that addressing environmental change favours adaptive and dynamic management approaches, while addressing shifting socio-economic and political conditions favours fixed long-term measures; considering both jointly requires a combination of dynamic-adaptive-fixed approaches. We outline a framework to integrate climate-responsive tools into a unified climate-resilient management approach using nested dynamic-adaptive-fixed management portfolios that improve management effectiveness and efficiency. This approach may help reduce future conflict between marine resource extractive and conservation goals through more explicit characterization of management trade-offs and identification of social and ecological tipping points.

Although climate-induced shifts in fish distribution have been widely reported at the population level, studies that account for ontogenetic shifts and subregional differences when assessing responses are rare.In this study, groundfish distributional changes in depth, latitude, and longitude were assessed at different size classes by species within nine subregions. We examined large, quality-controlled datasets of depth-stratified-random bottom trawl surveys conducted during summer in three large regions-the Gulf of Alaska and the west coasts of Canada and the United States-over the period 1996-2015, a time period punctuated by a marine "heat wave." Temporal biases in bottom temperature were minimized by subdividing each region into three subregions, each with short-duration surveys. Near-bottom temperatures, weighted by stratum area, were unsynchronized across subregions and exhibited varying subregional interannual variability. The weighted mean bottom depths in the subregions also vary largely among subregions. The centroids (centers of gravity) of groundfish distribution were weighted with catch per unit effort and stratum area for 10 commercially important groundfish species by size class and subregion. Our multivariate analyses showed that there were significant differences in aggregate fish movement responses to warm temperatures across subregions but not among species or sizes. Groundfish demonstrated poleward responses to warming temperatures only in a few subregions and moved shallower or deeper to seek colder waters. The temperature responses of groundfish depended on where they were. Under global warming, groundfish may form geographically distinct thermal ecoregions along the northeast Pacific shelf. Shallow-depth species exhibited greatly different distributional responses to temperature changes across subregions while deep-depth species of different subregions tend to have relatively similar temperature responses. Future climate studies would benefit by considering fish distributions on small subregional scales.

The potential influence of climate change on the future distribution and abundance of fish (and therefore commercial fisheries and food security) is increasingly recognized in the fishery management community. A changing climate will likely have differing effects on different species; some will flourish, some will flounder. Management targets for fishing mortality and spawning biomass are often calculated by assuming stationary population processes, but under climate change, this assumption may be violated. Non-stationary population processes can introduce bias into estimates of biomass from stock assessments and calculations of target fishing mortalities and biomasses. However, few accepted frameworks exist for incorporating the changing influence of the environment on exploited populations into management strategies. Identifying changes in population processes due to environmental influences is important in order to enable climate-enhanced management strategy evaluations to elucidate the potential benefits and costs of changing management targets. Cost/benefit analyses will also be useful when coincidentally caught species respond differently to environmental change.

Projections of the impacts of climate change on marine ecosystems are a key prerequisite for the planning of adaptation strategies, yet they are inevitably associated with uncertainty. Identifying, quantifying, and communicating this uncertainty is key to both evaluating the risk associated with a projection and building confidence in its robustness. We review how uncertainties in such projections are handled in marine science. We employ an approach developed in climate modelling by breaking uncertainty down into (i) structural (model) uncertainty, (ii) initialization and internal variability uncertainty, (iii) parametric uncertainty, and (iv) scenario uncertainty. For each uncertainty type, we then examine the current state-of-the-art in assessing and quantifying its relative importance. We consider whether the marine scientific community has addressed these types of uncertainty sufficiently and highlight the opportunities and challenges associated with doing a better job. We find that even within a relatively small field such as marine science, there are substantial differences between subdisciplines in the degree of attention given to each type of uncertainty. We find that initialization uncertainty is rarely treated explicitly and reducing this type of uncertainty may deliver gains on the seasonal-to-decadal time-scale. We conclude that all parts of marine science could benefit from a greater exchange of ideas, particularly concerning such a universal problem such as the treatment of uncertainty. Finally, marine science should strive to reach the point where scenario uncertainty is the dominant uncertainty in our projections.

Understanding demographic variation in recruitment and somatic growth is key to improving our understanding of population dynamics and forecasting ability. Although recruitment variability has been extensively studied, somatic growth variation has received less attention, in part because of difficulties in modeling growth from individual size-at-age estimates. Here we develop a Bayesian state-space approach to test for the prevalence of alternative forms of growth rate variability (e.g., annual, cohort-level, or in the first year recruited to the fishery) in size-at-age data. We apply this technique to 29 Pacific groundfish species across the California Current, Gulf of Alaska, and Bering Sea – Aleutian Islands marine ecosystems. About 40% of modeled stocks were estimated to exhibit temporal growth variation. In the majority of stocks, growth trends fluctuated annually across ages in a single year, suggesting that either there are shared environmental features that dictate growth across multiple ages or the presence of some systematic (within-year) observation errors. This method represents a novel way to use size-at-age data from fishery or other sources to test hypotheses about growth dynamics variability.

Characterizing spatial structure and delineating meaningful spatial boundaries have useful applications to understanding regional dynamics in marine systems, and are integral to ecosystem approaches to fisheries management. Physical structure and drivers combine with biological responses and interactions to organize marine systems in unique ways at multiple scales. We apply multivariate statistical methods to define spatially coherent ecological units or ecoregions in the eastern Bering Sea. We also illustrate a practical approach to integrate data on species distribution, habitat structure and physical forcing mechanisms to distinguish areas with distinct biogeography as one means to define management units in large marine ecosystems. We use random forests to quantify the relative importance of habitat and environmental variables to the distribution of individual species, and to quantify shifts in multispecies assemblages or community composition along environmental gradients. Threshold shifts in community composition are used to identify regions with distinct physical and biological attributes, and to evaluate the relative importance of predictor variables to determining regional boundaries. Depth, bottom temperature and frontal boundaries were dominant factors delineating distinct biological communities in this system, with a latitudinal divide at approximately 60°N. Our results indicate that distinct climatic periods will shift habitat gradients and that dynamic physical variables such as temperature and stratification are important to understanding temporal stability of ecoregion boundaries. We note distinct distribution patterns among functional guilds and also evidence for resource partitioning among individual species within each guild. By integrating physical and biological data to determine spatial patterns in community composition, we partition ecosystems along ecologically significant gradients. This may provide a basis for defining spatial management units or serve as a baseline index for analyses of structural shifts in the physical environment, species abundance and distribution, and community dynamics over time.

We investigated the hypothesis that synchronous recruitment is due to a shared susceptibility to environmental processes using stock–recruitment residuals for 52 marine fish stocks within three Northeast Pacific large marine ecosystems: the Eastern Bering Sea and Aleutian Islands, Gulf of Alaska, and California Current. There was moderate coherence in exceptionally strong and weak year-classes and correlations across stocks. Based on evidence of synchrony from these analyses, we used Bayesian hierarchical models to relate recruitment to environmental covariates for groups of stocks that may be similarly influenced by environmental processes based on their life histories. There were consistent relationships among stocks to the covariates, especially within the Gulf of Alaska and California Current. The best Gulf of Alaska model included Northeast Pacific sea surface height as a predictor of recruitment, and was particularly strong for stocks dependent on cross-shelf transport during the larval phase for recruitment. In the California Current the best-fit model included San Francisco coastal sea level height as a predictor, with higher recruitment for many stocks corresponding to anomalously high sea level the year before spawning and low sea level the year of spawning. The best Eastern Bering Sea and Aleutian Islands model included several environmental variables as covariates and there was some consistent response across stocks to these variables. Future research may be able to utilize these across-stock environmental influences, in conjunction with an understanding of ecological processes important across early life history stages, to improve identification of environmental drivers of recruitment.

Arctic and Antarctic marine systems have in common high latitudes, large seasonal changes in light levels, cold air and sea temperatures, and sea ice. In other ways, however, they are strikingly different, including their: age, extent, geological structure, ice stability, and foodweb structure. Both regions contain very rapidly warming areas and climate impacts have been reported, as have dramatic future projections. However, the combined effects of a changing climate on oceanographic processes and foodweb dynamics are likely to influence their future fisheries in very different ways. Differences in the life-history strategies of the key zooplankton species (Antarctic krill in the Southern Ocean and Calanus copepods in the Arctic) will likely affect future productivity of fishery species and fisheries. To explore future scenarios for each region, this paper: (i) considers differing characteristics (including geographic, physical, and biological) that define polar marine ecosystems and reviews known and projected impacts of climate change on key zooplankton species that may impact fished species; (ii) summarizes existing fishery resources; (iii) synthesizes this information to generate future scenarios for fisheries; and (iv) considers the implications for future fisheries management. Published studies suggest that if an increase in open water during summer in Arctic and Subarctic seas results in increased primary and secondary production, biomass may increase for some important commercial fish stocks and new mixes of species may become targeted. In contrast, published studies suggest that in the Southern Ocean the potential for existing species to adapt is mixed and that the potential for the invasion of large and highly productive pelagic finfish species appears low. Thus, future Southern Ocean fisheries may largely be dependent on existing species. It is clear from this review that new management approaches will be needed that account for the changing dynamics in these regions under climate change.

Hollowed, A. B., Barange, M., Beamish, R., Brander, K., Cochrane, K., Drinkwater, K., Foreman, M., Hare, J., Holt, J., Ito, S-I., Kim, S., King, J., Loeng, H., MacKenzie, B., Mueter, F., Okey, T., Peck, M. A., Radchenko, V., Rice, J., Schirripa, M., Yatsu, A., and Yamanaka, Y. 2013. Projected impacts of climate change on marine fish and fisheries. – ICES Journal of Marine Science, 70: 1023–1037. This paper reviews current literature on the projected effects of climate change on marine fish and shellfish, their fisheries, and fishery-dependent communities throughout the northern hemisphere. The review addresses the following issues: (i) expected impacts on ecosystem productivity and habitat quantity and quality; (ii) impacts of changes in production and habitat on marine fish and shellfish species including effects on the community species composition, spatial distributions, interactions, and vital rates of fish and shellfish; (iii) impacts on fisheries and their associated communities; (iv) implications for food security and associated changes; and (v) uncertainty and modelling skill assessment. Climate change will impact fish and shellfish, their fisheries, and fishery-dependent communities through a complex suite of linked processes. Integrated interdisciplinary research teams are forming in many regions to project these complex responses. National and international marine research organizations serve a key role in the coordination and integration of research to accelerate the production of projections of the effects of climate change on marine ecosystems and to move towards a future where relative impacts by region could be compared on a hemispheric or global level. Eight research foci were identified that will improve the projections of climate impacts on fish, fisheries, and fishery-dependent communities.

The ability of management strategies to achieve the fishery management goals are impacted by environmental variation and, therefore, also by global climate change. Management strategies can be modified to use environmental data using the “dynamic B0” concept, and changing the set of years used to define biomass reference points. Two approaches have been developed to apply management strategy evaluation to evaluate the impact of environmental variation on the performance of management strategies. The “mechanistic approach” estimates the relationship between the environment and elements of the population dynamics of the fished species and makes predictions for population trends using the outputs from global climate models. In contrast, the “empirical approach” examines possible broad scenarios without explicitly identifying mechanisms. Many reviewed studies have found that modifying management strategies to include environmental factors does not improve the ability to achieve management goals much, if at all, and only if the manner in which these factors drive the system is well known. As such, until the skill of stock projection models improves, it seems more appropriate to consider the implications of plausible broad forecasts related to how biological parameters may change in the future as a way to assess the robustness of management strategies, rather than attempting specific predictions per se.

An assessment of the potential for 17 fish or shellfish stocks or stock groups to move from the sub-Arctic areas into the Arctic Ocean was conducted. A panel of 34 experts was convened to assess the impact of climate change on the potential movement of the 17 stocks or stock groups. The panel considered the exposure of species to climate change, the sensitivity of species to these changes and the adaptive capacity of each stock or stock group. Based on expert opinions, the potential for expansion or movement into the Arctic was qualitatively ranked (low potential, potential, high potential). It is projected that the Arctic Ocean will become ice-free during the summer season, and when this happens new areas will open up for plankton production, which may lead to new feeding areas for fish stocks. Five stocks had a low potential to move to, or expand in, the high Arctic. Six species are considered as potential candidate species to move to, or expand in, the high Arctic. Six stocks had a high potential of establishing viable resident populations in the region. These six stocks exhibit life history characteristics that allow them to survive challenging environmental conditions that will continue to prevail in the north. This study suggests that several life history factors should be considered when assessing the potentiality of a species moving in response to changing climate conditions.

Severallinesofevidenceshowthatclimaticvariationandglobalwarmingcanhavea major effect on fisheries production and replenishment. To prevent overfishing and rebuild overfished stocks under changing and uncertain environmental conditions, new research partnerships between fisheries scientists and climate change experts are required. The Interna- tional Workshop on Climate and Oceanic Fisheries held in Rarotonga, Cook Islands, 3-5

Considerable progress has been made in integrating carbon, nutrient, phytoplankton and zooplankton dynamics into global-scale physical climate models. Scientists are exploring ways to extend the resolution of the biosphere within these Earth system models (ESMs) to include impacts on global distribution and abundance of commercially exploited fish and shellfish. This paper compares different methods for modeling fish and shellfish responses to climate change on global and regional scales. Several different modeling approaches are considered including: direct applications of ESM’s, use of ESM output for estimation of shifts in bioclimatic windows, using ESM outputs to force single- and multi-species stock projection models, and using ESM and physical climate model outputs to force regional bio-physical models of varying complexity and mechanistic resolution. We evaluate the utility of each of these modeling approaches in addressing nine key questions relevant to climate change impacts on living marine resources. No single modeling approach was capable of fully addressing each question. A blend of highly mechanistic and less computationally intensive methods is recommended to gain mechanistic insights and to identify model uncertainties.

This paper examines how climate variations influence the boundaries of suitable ocean habitat, and how these changes affect the spatial distribution and interactions between forage fishes in the southeastern Bering Sea shelf. The study focuses on the summer distributions of forage fish age-0 and age-1 walleye pollock, Theragra chalcogramma, and capelin, Mallotus villosus, observed during National Marine Fisheries Service summer acoustic trawl, surface trawl and bottom trawl surveys conducted in the Bering Sea between 2004 and 2009. We compare the responses of these forage fish to climate-induced shifts in ocean habitats. Habitat boundaries were defined using key explanatory variables including depth, bottom temperature and surface temperature, using general additive models. Bathymetry, bottom temperature and frontal zones formed boundaries between different groups of forage fishes. Age-0 pollock were dispersed throughout the middle domain (50–100 m depth) in well-stratified regions. In cold years the highest densities of age-0s were found in the southern regions of the middle domain waters in waters warmer than approximately 1 °C. In contrast, age-1 pollock were observed on the sea floor over the middle domain and in midwater in the northern outer domain in cold years and more broadly dispersed across the middle and outer domain in warm years. The demersal concentrations of age-1 pollock in the middle domain shows age-1 pollock tolerate a wide range of bottom temperatures. Midwater and demersal distributions of age-1 pollock exhibited a patchier distribution than age-0 pollock. Midwater concentrations of age-1 pollock tended to be associated with the outer domain and regions where higher levels of lower trophic level production are expected. Capelin were concentrated in the inner domain, a well-mixed region. The overlap of age-1 pollock and capelin was higher in cold years than in warm years.

Ianelli, J. N., Hollowed, A. B., Haynie, A. C., Mueter, F. J., and Bond, N. A. 2011. Evaluating management strategies for eastern Bering Sea walleye pollock (Theragra chalcogramma) in a changing environment. – ICES Journal of Marine Science, 68: 1297–1304. The impacts of climate change on fish and fisheries is expected to increase the demand for more accurate stock projections and harvest strategies that are robust to shifting production regimes. To address these concerns, we evaluate the performance of fishery management control rules for eastern Bering Sea walleye pollock stock under climate change. We compared the status quo policy with six alternative management strategies under two types of recruitment pattern simulations: one that follows temperature-induced trends and the other that follows a stationary recruitment pattern similar to historical observations. A subset of 82 Intergovernmental Panel on Climate Change climate models provided temperature inputs from which an additional 100 stochastic simulated recruitments were generated to obtain the same overall recruitment variability as observed for the stationary recruitment simulations. Results indicate that status quo management with static reference points and current ecosystem considerations will result in much lower average catches and an increased likelihood of fishery closures, should reduced recruitment because of warming conditions hold. Alternative reference point calculations and control rules have similar performance under stationary recruitment relative to status quo, but may offer significant gains under the changing environmental conditions.

Mueter, F. J., Bond, N. A., Ianelli, J. N., and Hollowed, A. B. 2011. Expected declines in recruitment of walleye pollock (Theragra chalcogramma) in the eastern Bering Sea under future climate change. – ICES Journal of Marine Science, 68: 1284–1296. A statistical model is developed to link recruitment of eastern Bering Sea walleye pollock (Theragra chalcogramma) to variability in late summer sea surface temperatures and to the biomass of major predators. The model is based on recent advances in the understanding of pollock recruitment, which suggest that warm spring conditions enhance the survival of early larvae, but high temperatures in late summer and autumn are associated with poor feeding conditions for young-of-year pollock and reduced recruitment in the following year. A statistical downscaling approach is used to generate an ensemble of late summer temperature forecasts through 2050, based on a range of IPCC climate projections. These forecasts are used to simulate future recruitment within an age-structured stock projection model that accounts for density-dependent effects (stock–recruitment relationship), the estimated effects of temperature and predation, and associated uncertainties. On average, recruitment in 2040–2050 should expectedly decline by 32–58% relative to a random recruitment scenario, depending on assumptions about the temperature relationship, the magnitude of density-dependence, and future changes in predator biomass. The approach illustrated here can be used to evaluate the performance of different management strategies and provide long-term strategic advice to managers confronted with a rapidly changing climate.

We consider the question of which quantitative modelling tools can be used to support an ecosystem approach to management (EAM), with a focus on evaluating the implication of decisions on the biological system being managed. Managers of federal fisheries in the eastern Bering Sea, USA, have adopted an EAM. The tools used to support EAM in the eastern Bering Sea serve as a guide to what types of models could be used elsewhere. A review of the role of natural science in the implementation of EAM shows that scientific advice enters into decision-making at a variety of steps. Single-species stock assessment and projection models are the most commonly used tools employed to inform managers. Comprehensive assessments (e.g. management strategy evaluation) are emerging as a new and potentially valuable analysis technique for use in assessing trade-offs of different strategic alternatives. In the case of management in the eastern Bering Sea, end-to-end models and coupled biophysical models have been used primarily to advance scientific understanding, but have not been applied in a management context. This review highlights that implementation of an EAM in a management environment such as eastern Bering Sea requires substantial commitments to the collection and analysis of data and support for a group of analysts with interdisciplinary training in population dynamics, oceanography and ecology. This review supports the growing recognition that a diverse suite of modelling tools is needed to address tactical and strategic management issues germane to the adoption of the ecosystem approach to fisheries management.

The study of climate impacts on Living Marine Resources (LMRs) has increased rapidly in recent years with the availability of climate model simulations contributed to the assessment reports of the Intergovernmental Panel on Climate Change (IPCC). Collaboration between climate and LMR scientists and shared understanding of critical challenges for such applications are essential for developing robust projections of climate impacts on LMRs. This paper assesses present approaches for generating projections of climate impacts on LMRs using IPCC-class climate models, recommends practices that should be followed for these applications, and identifies priority developments that could improve current projections. Understanding of the climate system and its representation within climate models has progressed to a point where many climate model outputs can now be used effectively to make LMR projections. However, uncertainty in climate model projections (particularly biases and inter-model spread at regional to local scales), coarse climate model resolution, and the uncertainty and potential complexity of the mechanisms underlying the response of LMRs to climate limit the robustness and precision of LMR projections. A variety of techniques including the analysis of multi-model ensembles, bias corrections, and statistical and dynamical downscaling can ameliorate some limitations, though the assumptions underlying these approaches and the sensitivity of results to their application must be assessed for each application. Developments in LMR science that could improve current projections of climate impacts on LMRs include improved understanding of the multi-scale mechanisms that link climate and LMRs and better representations of these mechanisms within more holistic LMR models. These developments require a strong baseline of field and laboratory observations including long time series and measurements over the broad range of spatial and temporal scales over which LMRs and climate interact. Priority developments for IPCC-class climate models include improved model accuracy (particularly at regional and local scales), inter-annual to decadal-scale predictions, and the continued development of earth system models capable of simulating the evolution of both the physical climate system and biosphere. Efforts to address these issues should occur in parallel and be informed by the continued application of existing climate and LMR models.

Zhang, C. I., Hollowed, A. B., Lee, J-B., and Kim, D-H. 2011. An IFRAME approach for assessing impacts of climate change on fisheries. – ICES Journal of Marine Science, 68: 1318–1328. A new assessment framework is proposed for evaluating the performance of management strategies relative to the goals of an ecosystem approach to management (EAM) under different climate change scenarios. Earlier studies have demonstrated how global climate model simulations from the Intergovernmental Panel on Climate Change can be used to force regional ocean circulation models and forecast regional changes in bottom-up forcing. We extend this approach to assess the ecosystem impacts of resource use and climate change in marine ecosystems, by developing an Integrated Fisheries Risk Analysis Method for Ecosystems (IFRAME) framework. The IFRAME approach tracks climate change impacts on the flow of energy through the planktonic foodweb using NEMURO and projects the implications of these shifts in bottom-up forcing on the fisheries foodweb using Ecopath with Ecosim. Resource management scenarios are developed and incorporated into the projection framework by characterizing the action for changes in fishing mortality or availability of resources. An integrated suite of ecosystem status indicators are proposed to assess the performance of management scenarios relative to the goals of an EAM. These ecosystem status indicators track four key management objectives of the ecosystem: sustainability, biodiversity, habitat quantity, and quality and socio-economic status.

Hollowed, A. B., Bond, N. A., Wilderbuer, T. K., Stockhausen, W. T., A'mar, Z. T., Beamish, R. J., Overland, J. E., and Schirripa, M. J. 2009. A framework for modelling fish and shellfish responses to future climate change. – ICES Journal of Marine Science, 66: 1584–1594. A framework is outlined for a unified approach to forecasting the implications of climate change on production of marine fish. The framework involves five steps: (i) identification of mechanisms underlying the reproductive success, growth, and distribution of major fish and shellfish populations, (ii) assessment of the feasibility of downscaling implications of climate scenarios derived from Intergovernmental Panel on Climate Change (IPCC) models for regional ecosystems to select and estimate relevant environmental variables, (iii) evaluation of climate model scenarios and select IPCC models that appear to provide valid representations of forcing for the region of study, (iv) extraction of environmental variables from climate scenarios and incorporation into projection models for fish and shellfish, and (v) evaluation of the mean, variance, and trend in fish and shellfish production under a changing ecosystem. This framework was applied to forecast summer sea surface temperature in the Bering Sea from 2001 to 2050. The mean summer surface temperature was predicted to increase by 2°C by 2050. The forecasting framework was also used to estimate the effects of climate change on production of northern rock sole (Lepidopsetta polyxystra) through projected changes in cross-shelf transport of larvae in the Bering Sea. Results suggest that climate change will lead to a modest increase in the production of strong year classes of northern rock sole.

Climate forcing of the California Current has been known to impact the distribution and abundance of a number of local fish populations, but the mechanisms involved remain poorly understood. Climate metrics such as the Pacific Decadal Oscillation (PDO) and the El Nino Southern Oscillation (ENSO) are usually used to represent climate processes and direct links are made between climate forcing and production variability. This involves aggregation of impacts across large spatial scales and range of species. However, fluctuations in productivity are often the result of changes in physical habitat. In order to fully understand the relationship between climate and productivity, habitat changes should be addressed. In this study we use a geostatistical approach to quantify adult Pacific hake habitat during different climate regimes. Several authors have suggested that the distribution and intensity of the sub-surface poleward flow (the undercurrent) plays a key role in defining adult hake habitat along the west coast of North America. Here we build a model designed to predict hake habitat distribution in space based on sub-surface poleward flow distribution and bottom depth. Our results show that hake habitat expands in 1998 El Nino year compared to 1995. Given the important predatory role that hake plays in the CC, the amount and distribution of adult hake habitat has large implications for the Pacific Northwest food web and could thus serve as an ecosystem indicator representing important physical–biological interactions. Spatially based ecosystem indicators such as the one we develop here address two important yet neglected areas in the ‘Ecosystem Indicators debate’: the importance of developing metrics explicitly representing spatial and environmental processes shaping ecosystem structure. Without these, our power to fully describe ecosystems will be limited.

It is now clear that fished populations can fluctuate more than unharvested stocks. However, it is not clear why. Here we distinguish among three major competing mechanisms for this phenomenon, by using the 50-year California Cooperative Oceanic Fisheries Investigations (CalCOFI) larval fish record. First, variable fishing pressure directly increases variability in exploited populations. Second, commercial fishing can decrease the average body size and age of a stock, causing the truncated population to track environmental fluctuations directly. Third, age-truncated or juvenescent populations have increasingly unstable population dynamics because of changing demographic parameters such as intrinsic growth rates. We find no evidence for the first hypothesis, limited evidence for the second and strong evidence for the third. Therefore, in California Current fisheries, increased temporal variability in the population does not arise from variable exploitation, nor does it reflect direct environmental tracking. More fundamentally, it arises from increased instability in dynamics. This finding has implications for resource management as an empirical example of how selective harvesting can alter the basic dynamics of exploited populations, and lead to unstable booms and busts that can precede systematic declines in stock levels.